org.apache.crunch.io.impl.DefaultFileReaderFactory.java Source code

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Here is the source code for org.apache.crunch.io.impl.DefaultFileReaderFactory.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.crunch.io.impl;

import com.google.common.base.Function;
import com.google.common.collect.Iterators;
import com.google.common.collect.Lists;
import com.google.common.collect.UnmodifiableIterator;
import org.apache.crunch.CrunchRuntimeException;
import org.apache.crunch.io.FileReaderFactory;
import org.apache.crunch.io.FormatBundle;
import org.apache.crunch.types.PType;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.mapreduce.InputFormat;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.TaskAttemptID;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.task.TaskAttemptContextImpl;
import org.apache.hadoop.util.ReflectionUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Iterator;

class DefaultFileReaderFactory<T> implements FileReaderFactory<T> {

    private static final Logger LOG = LoggerFactory.getLogger(DefaultFileReaderFactory.class);

    private final FormatBundle<? extends InputFormat> bundle;
    private final PType<T> ptype;

    public DefaultFileReaderFactory(FormatBundle<? extends InputFormat> bundle, PType<T> ptype) {
        this.bundle = bundle;
        this.ptype = ptype;
    }

    @Override
    public Iterator<T> read(FileSystem fs, Path path) {
        final Configuration conf = new Configuration(fs.getConf());
        bundle.configure(conf);
        ptype.initialize(conf);

        final InputFormat fmt = ReflectionUtils.newInstance(bundle.getFormatClass(), conf);
        final TaskAttemptContext ctxt = new TaskAttemptContextImpl(conf, new TaskAttemptID());
        try {
            Job job = new Job(conf);
            FileInputFormat.addInputPath(job, path);
            return Iterators.concat(Lists.transform(fmt.getSplits(job), new Function<InputSplit, Iterator<T>>() {
                @Override
                public Iterator<T> apply(InputSplit split) {
                    try {
                        RecordReader reader = fmt.createRecordReader(split, ctxt);
                        reader.initialize(split, ctxt);
                        return new RecordReaderIterator<T>(reader, ptype);
                    } catch (Exception e) {
                        LOG.error("Error reading split: " + split, e);
                        throw new CrunchRuntimeException(e);
                    }
                }
            }).iterator());
        } catch (Exception e) {
            LOG.error("Error reading path: " + path, e);
            throw new CrunchRuntimeException(e);
        }
    }

    private static class RecordReaderIterator<T> extends UnmodifiableIterator<T> {

        private final RecordReader reader;
        private final PType<T> ptype;
        private T cur;
        private boolean hasNext;

        public RecordReaderIterator(RecordReader reader, PType<T> ptype) {
            this.reader = reader;
            this.ptype = ptype;
            try {
                this.hasNext = reader.nextKeyValue();
                if (hasNext) {
                    Object converted = ptype.getConverter().convertInput(reader.getCurrentKey(),
                            reader.getCurrentValue());
                    this.cur = ptype.getInputMapFn().map(converted);
                }
            } catch (Exception e) {
                throw new CrunchRuntimeException(e);
            }
        }

        @Override
        public boolean hasNext() {
            return hasNext;
        }

        @Override
        public T next() {
            T ret = cur;
            try {
                hasNext = reader.nextKeyValue();
                if (hasNext) {
                    Object converted = ptype.getConverter().convertInput(reader.getCurrentKey(),
                            reader.getCurrentValue());
                    this.cur = ptype.getInputMapFn().map(converted);
                }
            } catch (Exception e) {
                throw new CrunchRuntimeException(e);
            }
            return ret;
        }
    }
}